JNTU
JNTU B.Tech II METALLURGY AND MATERIALS SCIENCE Previous Question Paper (May/June - 2019 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
PART A
Differentiate between metal and alloy.
Answer
A metal is a pure elemental substance characterized by high electrical and thermal conductivity, ductility, and metallic luster. An alloy is a metallic substance consisting of two or more elements, where at least one is a metal, combined to enhance specific mechanical or chemical properties like strength or corrosion resistance.
Lattice parameter of a FCC crystal is 3.61Å. Calculate atomic density in (111), (110) and (100) planes.
Answer
For an FCC crystal with lattice parameter a = 3.61 Å, the atomic density is calculated as the number of atoms per unit area of the plane. The atomic density is given by (Number of atoms in plane) / (Area of plane).
- (111) plane: Contains 2 atoms. Area = (√3/2)a2. Density = 2 / (0.866 × 3.612) ≈ 0.177 atoms/Å2.
- (110) plane: Contains 2 atoms. Area = (√2)a2. Density = 2 / (1.414 × 3.612) ≈ 0.108 atoms/Å2.
- (100) plane: Contains 2 atoms. Area = a2. Density = 2 / (3.612) ≈ 0.153 atoms/Å2.
Define Gibb’s phase Rule.
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List the different methods to construct the phase diagrams.
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Define hardenability and what factors it effects.
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Which alloy of Fe-Fe3C system has the lowest melting point?
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What is carbon equivalent?
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Distinguish between macrostructure and micro structure.
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Distinguish between glasses and cermets.
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Write the applications of polymers.
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PART B
State Hume-Rothery’s rules for the formation of substitutional solid solution.
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Define solid solution and explain about substitutional solid solutions with suitable examples.
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Calculate the packing factor for HCP.
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Explain about density calculations of crystal structures.
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Draw neatly and explain the phase diagram where two components are completely soluble in liquid state and partly insoluble in solid state (with example).
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What is Lever rule? Apply it to phase equilibrium in an alloy of 15% B and 85% A when a liquid of 45% B is in equilibrium with a solid solution of 95% A.
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What is Isomorphous alloy system? Explain with suitable example.
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Construct the TTT diagrams for 0.8wt% carbon steels.
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What is heat treatment and explain its effect?
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Distinguish between annealing and normalizing.
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Write the composition, properties and applications of the following:
Duralumin
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Cartridge brass.
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Differentiate between white Iron and grey cast Iron.
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Explain why extensive coring occurs in bronzes compared to brasses.
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Enumerate the characteristics, properties and applications of crystalline ceramics.
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Write short notes on:
cermets.
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polymers.
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